Many industries use trucks for the transportation of their goods. To transport a liquid, a truck is provided with a transport tank mounted to a frame of the truck or to a trailer of the truck. When the liquid is to be transported under pressure, the transport tank needs to be constructed to withstand this pressure. One example of such a liquid is a liquefied petroleum gas, such as propane. Typically, in order to withstand internal pressures, transport tanks are made of metal, such as carbon or stainless steel, and have a cylindrical central section and two generally curved ends. Although metal transport tanks such as the one described above are suitable for the transport of pressurized liquids they have some drawbacks.
In most jurisdictions, the total truck weight (truck plus payload) or total trailer weight (trailer plus payload) is not allowed to exceed a predetermined maximum weight. As a metal transport tank is heavy, the maximum weight of the payload that can be transported is less than could otherwise be transported if the transport tank was lighter. Also, a metal transport tank tends to corrode over time which requires maintenance, repair, and in some cases replacement of the tank.
One solution to at least some of the above-mentioned drawbacks of metal transport tanks consist is making the transport tank out of composite material. For tanks of the same volume, composite transport tanks are lighter than metal transport tanks. As a result, by using a composite transport tank the maximum weight of the payload that can be transported can be increased. Also, composite materials are typically less susceptible to corrosion than metals.
In order to attach a transport tank to a frame or trailer of a truck, one method consists in providing metal cradles connected to the tank and which provide connections for connecting to the trailer or frame. In metal transport tanks, the cradles are welded to the tank body.
However, in composite transport tanks this arrangement cannot be used. As would be understood, metal cradles cannot be welded to a composite material tank body.
Therefore, there is a need for a cradle assembly for mounting a transport tank made of composite material to a truck.
Also, due to the relatively low temperatures of some of the pressurized liquids that can be transported in such transport tanks and to the wide range of ambient temperatures in which the transport tank is to be used, a transport tank expands and contracts during use. For example, an empty tank which is filled with a low temperature pressurized liquid will contract. The pressure inside the transport tank also affects its volume. Additionally, the operational loads applied to the cradle assembly also vary (i.e. full tank versus empty tank).
Therefore, there is a need for a cradle assembly that can accommodate the expansion and contraction and the varying operational loads of a transport tank.